1. Field of the Invention
The invention is directed to the field of connecting and disconnecting high voltage electrical cables to high voltage electrical terminals and, more particularly, to the connection and disconnection of large, heavy high voltage electrical cables onto transformers, switch gear and the like.
2. Description of the Prior Art
Prior art techniques for connecting large, heavy high voltage cables used in 600 Amp electrical systems employed a standard T-shaped connector 10 as is shown in FIG. Connector 10 had a high voltage electrical cable receiving leg 12 into which a high voltage electrical cable 14 was inserted. At one end of cable 14 a terminator or electrical crimp connector 16 was placed. Crimp connector 16 was coupled to the bared central conductor of cable 14 by crimping crimp barrel 18 of connector 16 to such bared conductor as is well known in the art. Connector 16 also includes a lug 20 through which extends an internally threaded aperture 22.
Connector 10 further comprises an electrical terminal receiving leg 24 which includes a receptacle 26 contoured to mate with high voltage terminal 28. Terminal 28 which could be a transformer bushing or switch gear bushing or the like is mounted upon a support 30 which can be a wall of the enclosure for such equipment. Terminal 28 is made of a shell 32 of epoxy or similar insulating material and contains a core 34 of metal with an internally threaded aperture 36 therein.
A third leg 38, aligned with electrical terminal receiving leg 24 also contains a receptacle 40 and is the mirror image of leg 38 and the connector 10 could be rotated so that leg 38 can be employed as a terminal receiving leg if desired. The central bore of leg 12 communicates with receptacles 26 of leg 24 and 40 of leg 38 such that the threaded aperture 22 of lug 20 can be inserted into the jointure of receptacles 26 and 40 when cable 14 is fully positioned in leg 12.
A fastening means in the form of dead plug 42 is used to join high voltage electrical cable 14 to terminal 28. Plug 42 has a body shell 44 fabricated of insulating material and a metal core 46 with an externally threaded portion 48 at one end and a voltage test point 50 at the other. To fasten cable 14 to terminal 28, the cable 14 with terminator 16 installed is placed into the bore of cable receiving leg 12 and advanced until the lug 20 enters the jointure between receptacles 26 and 40 and threaded aperture 22 is aligned with the central axis of receptacles 26 and 40. Plug 42 is now introduced into leg 38 and rotated by a tool (not shown) applied to test point 50. Externally threaded portion 48 engages first internally threaded aperture 22 of lug 20 and then internally threaded aperture 36 of terminal 28. As the plug 42 gets closer to its final assembly position, the engagement of the outer surface of the insulating body shell 44 and the inner surface of receptacle 40 produce a great deal of resistance and friction making assembly and later disassembly difficult. Further, the externally threaded portion 48 offers no assistance in assembling the connector 10 to terminal 28 or in its later disassembly.
Since voltage test point 50 may be hot because of its direct connection to the high voltage cable 14, an insulating cap 52 is used. Because the shield is interrupted to provide access to the test point 50, a cap 52 of semi-conductive elastomeric material such as EPDM with carbon black is employed. Cap 52 fits over the outer surface of leg 38 and is installed by the engagement of a hot stick (not shown) with the ring 54. Cap 52 is removed when plug 42 is to be installed or removed or when it is desired to probe the test point 50 to determine the presence of a voltage at the cable 14 and/or terminal 28. Alternatively, instead of the dead plug 42 a load break tap reducing plug LTRP (not shown) or other similar device could be employed.
To permit the cable receiving leg 12 to receive a wide range of cable diameters, it was common to make the diameter of the bore large enough to handle the diameter of the largest terminator 16 required for the largest diameter cable to be used with the connector 10. Then a cable adapter was used to match the outside diameter of the cable to be used with the inside diameter of the bore of the cable receiving leg 12. This required that a large number of cable adapters be available and increased the possibility of the introduction of dirt and other contaminants into the connector because of the two interfaces, one between the cable surface and the bore of the cable adapter and a second between the surface of the cable adapter and bore of the cable receiving leg 12. Further, since plug 42 and connector 10 were separate, assembly of the threaded portion 48 of plug 42 into threaded aperture 36 of terminal 28 did not assist in the assembly of connector 10 to terminal 28 until plug 42 was almost completely seated and did not assist at any time in the disassembly of connector 10 from terminal 28.